Entries in electric barrier
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The last line of defense against Asian carp entering Lake Michigan isn’t impenetrable, according to a new report by the U.S. Army Corps of Engineers and the U.S. Fish and Wildlife Service.

Fish can pass through the electric barrier unharmed when they get caught in the wakes of barges passing through. And that’s not all. Metal barges can deplete the charge, and small fish aren’t always susceptible.

"Initial findings indicate that vessel-induced residual flows can trap fish and transport them beyond the electrical barriers, and that certain barge configurations may impact barrier electric field strength,” says an interim report based on laboratory and field experiments.

“Additionally, the preliminary (sonar camera) findings identified the potential for small fish (between 2-4 inches in length) to pass the barrier array in large groups, or schools."

The Corps emphasizes that the findings are preliminary, with more work to be done with the barge community and the Coast Guard to see how the barrier can be strengthened.

“There is no evidence that Asian Carp are bypassing the barriers; nor is there any indication Asian carp are in the vicinity of the barriers,” the agency says. “The closest adult Asian carp found in the Illinois River are about 55 miles from Lake Michigan, and no small Asian carp have been observed closer than 131 miles from Lake Michigan.”

Critics point out that water samples taken near the barrier and in a canal on the lake side of the barrier have tested positive for the exotic fish. Plus, poisoning of the canal in 2009 revealed an Asian carp carcass.

Oh, yeah! That electric barrier is going to keep Asian carp from entering Lake Michigan via a manmade connection to the Mississippi River basin.

Or maybe not.

A video obtained by the Milwaukee Journal Sentinel shows small fish swimming through the electrified water, just 35 miles downstream from Chicago’s lakeshore.

And no one said that the invaders must be adult fish.

“The only thing holding back the Asian carp at the moment is the electric barrier, but few people beyond Illinois politicians, the canal-dependent barge industry, and the Army Corps are buying the idea that the barrier is doing its job. Many worry the agency's continued confidence in this leaky, last line of defense will take a tragic toll on the Great Lakes, the world's largest freshwater system,” said the newspaper.

"Initial findings indicate that vessel-induced residual flows can trap fish and transport them beyond the electrical barriers, and that certain barge configurations may impact barrier electric field strength. Additionally, the preliminary (sonar camera) findings identified the potential for small fish (between 2-4 inches in length) to pass the barrier array in large groups, or schools."

Crews dropped in a camera 10 minutes at a time to see what was happening. In 61 percent of the 72 samples, they saw entire schools of fish, “not believed to be Asian carp,” swimming through.

But not to worry:

"There is no evidence that Asian carp are bypassing the barriers. Nor is there any indication that Asian carp are in the vicinity of the barriers," states the report. "The closest adult Asian carp found in the Illinois River are about 55 miles from Lake Michigan, and no small Asian carp have been observed closer than 131 miles from Lake Michigan."

So . . . it’s okay that we are spending millions of dollars to maintain a barrier that doesn’t work because, well, it doesn’t have to work because the Corps says the invaders are far, far away and don’t pose a threat.

Gee, that makes me feel so much better. I have to wonder, though, if the Corps is as competent at estimating the threat as it is at defending against it.

Asian carp have been found in fisheries from Colorado to New Jersey and from North Dakota to Florida, according to a map released recently by the U.S. Army Corps of Engineers, the U.S. Geological Survey, and the Illinois Department of Natural Resources.

“Asian Carp Distribution in North America” displays the presence of bighead and silver carp at all life stages, as well as black carp and grass carp occurrences. Since three bighead carp have been collected in the western basin over the years by commercial fishermen, Lake Erie is one of the green shaded areas, which indicates the presence of at least one adult fish. (This is not the map shown above. Go to link to see more detailed map.)

Not surprisingly, the most intense infestation is in the Mississippi and Missouri River watersheds, including the Illinois River, which connects to Lake Michigan via the Chicago Sanitary and Ship Canal.

On the positive side, no Asian carp have been found above the canal’s electric barriers during the past two years, despite hundreds of interagency monitoring trips, including 192 hours of electrofishing and 82 miles of netting.

But on the southeast side of the Mississippi River watershed, meanwhile, Asian carp are a growing problem for the Tennessee River and especially Kentucky Lake.

"Asian Carp by the thousands are flooding Kentucky Lake, causing a problem for fishermen, regular boaters and the other fish. With no natural predators the Asian carp are single-handedly eating the entire food supply, reports WBBJ.

As the U.S. Army Corps of Engineers continues to study the best ways to keep Asian carp out of the Great Lakes, those rascally silver and bighead carp aren’t waiting to see what the agency comes up with to replace and/or complement what seems to be an ineffective electric barrier.

Here’s the latest from the Milwaukee Journal-Sentinel:

“While it's been nearly two years since crews landed the only live Asian carp specimen above an electric barrier on the Chicago Sanitary and Ship Canal, DNA evidence of the jumbo carp continues to come in --- and the percentage of DNA-positive water samples taken above the barrier this year appears to have grown tenfold over last year.

“The Army Corps of Engineers reported that of the 2,378 water samples taken throughout 2011 in the canal system above the electric barrier, a total of 34 samples were positive. This year, after just one day of sampling the waters above the barrier, the Army Corps reports it landed 17 positive results from 114 water samples.

“In other words, the percentage of samples that tested positive for Asian carp DNA last year was about 1.5%. This year, so far, it has jumped to almost 15%.”